Effects of Nonionic Micelles on Dephosphorylation and Aromatic Nucleophilic Substitution

Foroudian, Houshang J.; Gillitt, Nicholas D.; Bunton, Clifford A.

doi:10.1006/jcis.2002.8306

Cited by 18 publications

(12 citation statements)

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“…The effect of headgroup size on rate constants for ether formation is opposite to that with EO surfactants, where reaction was faster with surfactants having a shorter headgroup [12,14]. Reaction in C 12 G 3 is faster than in C 9 G 1 and C 12 G 2 .…”

Section: Resultsmentioning

confidence: 51%

“…Although all solutes enter the palisade layer, concentrations of very hydrophilic ions are generally less in the palisade layer of a nonionic surfactant colloid than in the bulk solvent [12,19]. The observed differences in rate constants supports formation of ethers on all of the sugars in the headgroups; breakdown of ethers close to the water interface (C 9 G 1 ) should be faster than those closer to the hydrophobic region because they are in effectively much higher OH − concentrations.…”

Section: Resultsmentioning

confidence: 84%

“…Ether formation was monitored by the absorbance at the isosbestic point (323 nm) and the formation of 2,4-phenoxide ion was followed at 358 nm. Table 1 gives rate constants for reactions with C 9 G 1 , C 12 G 1 , and C 12 G 3 , and those of C 12 E 10 and C 12 E 23, obtained earlier [12,14]. Reactions were run under first order conditions with respect to DNCB and plots fitted first order kinetics, indicating that reactions give primarily one intermediate ether, or that ethers are formed, and decompose to phenoxide ion, with similar rate constants.…”

Section: Kineticsmentioning

confidence: 97%

“…The reaction of 2,4-dinitrochlorobenzene (DNCB) with nonionic ethylene oxide surfactants (EO) at high pH initially gives a surfactantdinitrophenyl ether, which [12][13][14] slowly reacts with OH − giving 2,4-dinitrophenoxide ion (Eq. (1) [12][13][14]:…”

Section: Introductionmentioning

confidence: 99%

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Aromatic nucleophilic substitution in nonionic alkylglucoside micelles

Whiddon

Bunton

Söderman

2004

Journal of Colloid and Interface Science

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Section: Resultsmentioning

confidence: 51%

Section: Resultsmentioning

confidence: 84%

Section: Kineticsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Aromatic nucleophilic substitution in nonionic alkylglucoside micelles

Whiddon

Bunton

Söderman

2004

Journal of Colloid and Interface Science

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“…Bunton, Savelli and others have shown this to be the case for reactions in micellar media. [26,[35][36][37][38] For instance, the type of reaction medium -homogeneous solution or micellar solution based on cationic surfactant -has been found to be decisive of the reaction of sulfonate esters in the presence of equimolar amounts of bromide and hydroxy ions. Without surfactant present attack by hydroxy ions dominates.…”

Section: Microemulsion Catalysismentioning

confidence: 99%

Organic Reactions in Microemulsions

Holmberg

2007

Eur J Org Chem

102

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Microemulsions, i.e., thermodynamically stable, one‐phase mixtures of oil, water and surfactants, are useful as reaction media as a way to overcome the reactant incompatibility problem that one frequently encounters in organic synthesis. The use of a microemulsion can be seen as an alternative to phase‐transfer catalysis, i.e., use of a two‐phase system with added phase‐transfer agent. The microemulsion approach and phase‐transfer catalysis can also be combined, i.e., the reaction can be performed in a microemulsion in the presence of a small amount of a phase‐transfer agent. A very high reaction rate may then be obtained. The reaction rate in a microemulsion is often influenced by the charge at the interface and this charge depends on the surfactant used. For instance, reactions involving negatively charged species will be accelerated by the use of a cationic surfactant. This effect is analogous to micellar catalysis and may be termed microemulsion catalysis. The acceleration is more pronounced when the surfactant counterion is small and weakly polarizable. Microemulsions can also be used to induce regiospecificity of organic reactions. Organic molecules with one more polar and one less polar end will accumulate at the oil‐water interface of microemulsions. They will orient at the interface so that the polar part of the molecule extends into the water domain and the nonpolar part extends into the hydrocarbon domain. A water‐soluble reagent will react from the “water side”, i.e., attack the polar part of the amphiphilic molecule, and a reagent soluble in hydrocarbon will react at the other end of the amphiphilic molecule. This review demonstrates that microemulsions can be a useful for (i) overcoming reactant incompatibility, (ii) speeding up reactions of one polar and one apolar reactant (microemulsion catalysis), and (iii) inducing regiospecificity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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